I am the proud owner of a shiny new SE84ZS. Steve graciousely agreed to provide an example in kit form. I spent almost a week carefully assembling my new baby. The results have been good, yet a little confusing for me as I am new to the world of SET.

The first thing I noticed with this amp is that it is nearly stone quiet. With my Klipsch Fortes connected I struggled to hear any noise even with my ear against the speakers! Very impressive.

My first few hours of listening impressed me with a very musical sound and surprising sound stage. However, I could only achieve very moderate listening levels. I expected more volume with these speakers. Turning the volume up past about 25% produced audible distortion in the mid-freqs. A descent pair of interconnects seamed to resolve the distortion. These interconnects are chinese made "Acoustic Research" brand purchased from Best Buy. (Please don't cringe!)

I was using my Samsung CD/DVD player temporarily. It sounded OK, but not stellar. I received an OPPO HD-750 universal player and now I'm using that. While it is not the ultimate source it is pretty darned good for $149!

The SE84ZS has been on-line for over a week now. I estimate around 20 to 30 hours of actual use. I think I hear changes already. The amp is somehow "smoother". But I am quite confused now as it seems I have lost some loudness. I find this much more noticable between one recording and another. Swapping CD playes makes no difference in sound level. Is there REALLY that much difference between CDs? I never took notice of that with my 100W sandbox. The change is significant... turning the volume know past 25% make almost no difference. On many recordings I can turn the know all the way up and the volume stays the same. There is no evidence of audible distortion. No even close to clipping. Bass is very week on these recordings.

Part of it could be something I've bolluxed up. I discoverd last night that the inputs that are suposed to be "direct" are also following the volume knob. I will be investigating that this weekend. I suspect I've connected the inputs to the wrong poles of the volume pot or someting along those lines. (Before jumping to conclusions... my voltages all checked out very close to spec.)

I will also be replacing my 25-year old speaker wire (double twisted pairs of ?? guage made by Monster - please don't cringe again!). I'm taking the simple approach and will use 10 guage copper speaker wire from m local electronics supply store. Is it possible that my crappy speaker cables are attenuating the signal enough to be noticable?

KD in San Antonio ???

I am still learning. Any advice or encouragement would be most welcomed!

Nothing wrong with monster speaker cables IMHO. But you do know that to achieve a "perceived "doubling in volume you need 10 X the power? A further note is that (I´m guessing here as I have the old select's) the Select needs 2.5 volts to achieve maximum power? most cd players only put out 2v at the most. Check your Cd player specks and let us know

[quote author=Rap link=1171040859/0#2 date=1171038290]Nothing wrong with monster speaker cables IMHO. But you do know that to achieve a "perceived "doubling in volume you need 10 X the power? A further note is that (I´m guessing here as I have the old select's) the Select needs 2.5 volts to achieve maximum power? most cd players only put out 2v at the most. Check your Cd player specks and let us know [/quote]My speaker cables are so old they show grotesque evidence of corrosion and the insulation is becoming supsect. I am replacing them for good measure, if nothing else.Your point about volume vs power is well taken. I realize there are limitations to what I can reasonably expect. My main difficulty is my inexperience with low powered SET and how to quantify my expectations to what is reasonable.My objectives at this point is to coax as much out of my system as I can with my modest budget.I haven't found specifics for the OPPO CD player. The owners manual is silent on that subject. I sent email to OPPO Digital Customer Support. Hopefully they will enlighten me.Thank you for your comments and best regards to you.KDSan Antonio, TX

If you're game for some further experimentation, try some CAT5(Plenum rated) speaker wire as well as the #10. A single conductor pair from the bundle of the 4 UTP can be more than adequate for short runs, and the left over pairs can be used for DIY interconnects. :)

25 years is enough time for the insulating jacket on almost speaker wire to leak oxygen and any other atmospheric contaminants to the surface of the copper conductors. In some cases you can actually see a dull green tinge of oxidization on the copper, or even worse chemical efflorescence in the case of soldered connections. In addition, there have been a wide variety of plastic compounds used in the insulation (dielectric), many of which can chemically and physically break down over time.

Any combination of these factors can certainly affect the sonic performance of the cabling.

p.s. ya beat me to the punch.

seriously, try the CAT 5 - more than a few Zen users are quite happy with the low priced spread. If you want to get audio-tweakish, you could always get some cryo'd.

kd...it is also quite possible one or more of the tubes is not good. this can happen in transit. with sharp volume decreases it could indeed be the rectifier tube or driver tube that is causing your issue (although i would expect some noise with the driver tube). the select still comes to full power with 2 volts of input from source so with those klipsch speakers you should be getting very loud.

[quote author=MikeW link=1171040859/0#5 date=1171043311]kd...it is also quite possible one or more of the tubes is not good. this can happen in transit. with sharp volume decreases it could indeed be the rectifier tube or driver tube that is causing your issue (although i would expect some noise with the driver tube). the select still comes to full power with 2 volts of input from source so with those klipsch speakers you should be getting very loud. [/quote]Sounds like I might need to talk to Steve!

[quote author=Rap link=1171040859/0#2 date=1171038290]A further note is that (I´m guessing here as I have the old select's) the Select needs 2.5 volts to achieve maximum power? most cd players only put out 2v at the most. Check your Cd player specks and let us know [/quote]

Just for clarity sake, both the older SE84CS and also the newer SE84ZS if working properly should both come to full power with 2 volts at the input, so almost any cd player oughta do it.

Just a note about volume and maximum power. Don't go by where any volume knobs are, they are simply an indication of gain and depending on the circuit one knob at 20% might be the same gain as another knob at 70%.

If your amp delivers more than it's maximum rated power it will clip, which it sounds like it is doing in the mids as you describe. It is not important where any knobs are, it is important what sort of volumes you are getting. It would be a good idea to get a cheap SPL meter from Rat Shack (~$20), and measure the volume where clipping is happening. It should be at least 95 dB I would think with Forte's, for some this is very loud and for others it's not very loud at all. It's fair to say if you are in the latter group, you are going to need more power than the Zen is capable of, and for all of it's strengths (and there are many of course), it will obviously not impress in power output. More efficient speakers can help somewhat, but that will only make a few dB's difference so if 95 isn't cutting it you might not be an ideal SET candidate. On the other hand, if it is clipping somewhat before 95 dB, you have a problem with your amp and could benefit from a call to Steve. Did you check your voltages?

selmerdave,I think maybe you haven't been to "Electrode Hut" in a while. SPL meters are $44.99 - $49.99. That's more than I had hoped to spend on something that I will seldom use and ultimately might not result in any improvement in my listening pleasure. (OK... translate that as "cheapskate" )

However, I think you are right on the money. Getting a true reading is infinitely better than trying to descibe what I think I have. I'll be checking around locally and at work to see if a meter can be borrowed.

The clipping question is still a question. On most CDs I can turn the gain know all the way up and hear no clipping. Also, there is no change from about 25% to 100%. I don't know if that is normal with the ZEN SE84ZS or not? Clipping, if it is happening must be extremely sublte with this amp. It is nothing like I've heard on SS equipment.

I tried giving Steve a call but I never seem to catch him. (My recent experience has been that I have better luck catching him than leaving a message on his voice mail.)

I am undaunted. I replaced the old corroded monster cable with 10 gage copper. This made an encremental improvement in sonic performance. It's not louder but my initial impression is that the bass is a little stronger and more natural.

I did check my voltages when I initially completed the amp. In my excitement to hear my system, I did not write them down. I will record them when I double check voltages, hopefully this coming weekend.

I found my copy of Joe's Garage. (When you have teenagers, you sometimes have to search for your CDs!) I've been wanting hear that one since I've not listened to it in a loooong time.

With the crossover upgrade, the "higher bias" switch position sounds pretty good. I've been listening in that mode most of the time since the crossover upgrade to Hovland caps. I was surprised at the volume levels acheivable with that particular CD! The ZEN amp rocks!

The SE84ZS can really drive the Fortes to considerable levels without clipping. Anyone that doesn't believe that just hasn't experienced it. It took me awhile to get things right and also the amp needed time to settle in. Now I am just amazed.

I also tried some SACDs. Yes, this format DOES make a difference.

I am very happy with my little ZEN amp, now. It's time to just listen to the music and see how more hours on the amp (and the new crossovers) develops over time.

The next project is a dedicated listening room. The wife has decided that the best solution is to build a studio out back. Well... I guess I'll give in to that one. KD

If you look at the master catalog on the Decware site you can find the upgrade kit that even includes the 5U4 rectifier for $78 dollars that will upgrade your SE84B or SE84C to the SE84CS which is the same amp as the ZS. The difference in the CS and ZS according to Decware is just the new chassis.

There is also a schematic that shows the differences in the SE84CS manual. If you send me an email address I can send you a PDF file of that manual.

The SE84ZS went belly-up recently. The final event was a spectaculary screeching sound upon power up, with me scrambling to disconnect everything that wasn't permanently connected. Then... silence.

Steve D helped me diagnos the problem. A burned resistor pointed to a shorted output tube. (1Kohm, 2W) Yes, one of the 6N15NP tubes has a short between pins 2 and 9. Steve tells me this is rare but does happen. New tubes are being purchased from Decware and I hope to be back in business soon.

Now I can't help but wonder how long has this impending tube failure existed and could it have effected the amp performance all along?

I've often heard defects in the mid range that a newbie, like myself, could have mistaken for clipping or other things? Perhaps so.

The Zen amp, prior to this tube failure, has provided some stunning performance. However, it has been intermixed with some frustrating times of mediocre performance. Many of the problems were from the rest of my system... oxidized speaker cables, blown tweeters, etc.

I would like to hear from those with experience how a latent tube failure such as this could effect the overall performance. Although, with new tubes on the way I suppose it is just a curiousity.

I will offer this much from my experience... If you have had troubles, or you are hesitant to get into tube gear or particulary Decware equipment, do not let my experience deter you! My problems have been mostly from putting a very revealing amp (SE84ZS) into a mixture of very old and neglected equipment. Combine that with my truly limited knowledge and things just take a while to sort out. I've been chasing bugs in every direction! Steve Deckert has been truly patient with me a extrememly helpful.

I'm looking forward to gettng back on track. I've had enough of those magical moments with this little amp to understand that it is worth all the effort I have had to do!

It is *definitely* better to shut the power down before doing any of the above (perhaps you did), and *definitely definitely* not a good idea to ever disconnect speakers from the amp if it is powered on or have the amp on without speakers connected.

Quote:

I would like to hear from those with experience how a latent tube failure such as this could effect the overall performance. Although, with new tubes on the way I suppose it is just a curiousity.

It is certainly a better scenario than had the same thing happened to a transistor in a PCB-board sand amp. The nice thing is you can just pop out the bad tube, pop in the good tube and you're back in business. Whether anything else got damaged I wouldn't know and perhaps the technically informed can comment on likelihoods, but I think the main thing I would be concerned about would be if you disconnected the speaker wire with it on. If you put in the new tube, and you get sound, you're okay on that count.

Turned off power first. Since the schreeching noise continued, I pulled inputs first, then speaker wires. By the time I got the speaker terminals unscrewed, things had settled down. A harrowing experience to say the least.

The resistor was the only thing damaged in the amp. A simple job to replace. It is likely that the tube failed first and then the resistor was overloaded and subsequently failed.

While I'm waiting for new tubes, I'm looking into a tweeter problem again. One of them quit. I'll be troubleshooting that tonight. Since I built a new crossover, I might have a problem there. I'll check the tweeter first and then look at the crossover.

It is possible, in my understanding, to power on a ZEN amp without speakers hooked up. In fact, in the SE84C assembly instructions, Steve instructs to check voltages across resistors and there it says, "To test these voltages, you should have the volume pot turned all the way off, and no load hooked to the amplifier". "No load" means no speakers hooked up to me. I think the key is to have the volume post all the way off.